I almost always try one after 5 days, there's usually always carbonation except for the batch I made after the temperature break when my basement temperature went from 72 down to 62. They aren't fully carbonated, but I still always do it. :)
As long as you stirred it up good and it didn't scorch the bottom of your pot you should be fine. It's a good idea to take the pot off the heat while you add the extract and stir it, then bring it back to a boil so you don't get any scorching.
My first porter and brown had an off taste because I was fermenting at 70-74 ambient. I could taste it in my pale ale also but not as bad... Once I got my temperature under control it went away.
I bought the one this guy used for ~$100 a walmart on sale a couple months ago. Right now i'm using it as a fermentation chamber until I find a cheap chest freezer, then I'm going to convert it.
http://www.instructables.com/id/Kegerator-GE-WMR04GAVBB-45-cu-ft-compact-fridg/
I just did my second boil with the sq-14 last night and had some issues. My first boil went great, kept 7 gallons boiling just fine. Last night it was a lot colder (probably high 30s low 40s) and I couldn't keep a boil going without the lid partially on. Is that normal? Every time I tried to...
I'm not sure about your direct questions, but I saw a thread with 2.5 gallon jars the other day
https://www.homebrewtalk.com/f51/2-1-2-gallon-montana-jar-fermenter-200328/
Of course you could probably only do 2 gallon batches in those.
I think the easiest way to scale down ingredients is to...